Test and simulation of High-Tc superconducting power charging system for solar energy application

Haeryong Jeon,Young Gun Park,Jeyull Lee,Yong Soo Yoon,Yoon Do Chung,Tae Kuk Ko 한국초전도저온학회 (구 한국초전도저온공학회) 2015 한국초전도저온공학회논문지 Vol.17 No.3

Test and simulation of High-Tc superconducting power charging system for solar energy application

Jeon, Haeryong,Park, Young Gun,Lee, Jeyull,Yoon, Yong Soo,Chung, Yoon Do,Ko, Tae Kuk The Korea Institute of Applied Superconductivity a 2015 한국초전도저온공학회논문지 Vol.17 No.3

This paper deals with high-Tc superconducting (HTS) power charging system with GdBCO magnet, photo-voltaic (PV) controller, and solar panels to charge solar energy. When combining the HTS magnet and the solar energy charging system, additional power source is not required therefore it is possible to obtain high power efficiency. Since there is no resistance in superconducting magnet carrying DC transport current the energy losses caused by joule heating can be reduced. In this paper, the charging characteristics of HTS power charging system was simulated by using PSIM. The charging current of HTS superconducting power charging system is measured and compared with the simulation results. Using the simulation of HTS power charging system, it can be applied to the solar energy applications.

PID Control of an Electromagnet-Based Rotary HTS Flux Pump for Maintaining Constant Field in HTS Synchronous Motors

Jeon, Haeryong,Lee, Jeyull,Han, Seunghak,Kim, Ji Hyung,Hyeon, Chang Ju,Kim, Ho Min,Kang, Hyoungku,Ko, Tae Kuk,Yoon, Yong Soo Institute of Electrical and Electronics Engineers 2018 IEEE transactions on applied superconductivity Vol.28 No.4

<P>Rotary HTS flux pumps are suitable for cryogenic applications, where it is difficult to implement direct physical connections between the device in question and an external power supply. Here we examine the proportional-integral-derivative (PID) control of a rotary HTS flux pump to compensate for a change in the current in the HTS field coil of a synchronous motor under operating conditions. The field coil current must be maintained constant to prevent output fluctuation of the synchronous motor. In this context, a prototype of the rotary HTS flux pump with rotating HTS tape is constructed for a synchronous motor in this study. A 600-turn electromagnet is used to inject magnetic flux into the HTS tape to charge the HTS coil. The magnetic field of the electromagnet is controlled via PID control with respect to the rotational speed and rotating direction of the machine. As a result, we successfully compensate for change in the current of the HTS coil by controlling the magnetic field of the electromagnet, while the rotating speed and direction are varied.</P>

Methods for Increasing the Saturation Current and Charging Speed of a Rotary HTS Flux-Pump to Charge the Field Coil of a Synchronous Motor

Jeon, Haeryong,Lee, Jeyull,Han, Seunghak,Kim, Ji Hyung,Hyeon, Chang Ju,Kim, Ho Min,Park, Dongkeun,Chung, Yoon Do,Ko, Tae Kuk,Yoon, Yong Soo IEEE 2018 IEEE transactions on applied superconductivity Vol.28 No.3

<P>The rotary flux-pump using HTS tape has been studied for superconducting rotating machinery application. The charging speed and saturation current of the rotary HTS flux-pump is closely related to magnetic flux linkage passing through the HTS tape. To analyze charging parameters that effect pumping rate and saturation current of the flux-pump, methods of changing the rotating speed, shape of permanent magnet, width of HTS tape, and magnetic flux intensity have been investigated in previous studies <xref ref-type='bibr' rid='ref1 ref2'>[1]</xref>– <xref ref-type='bibr' rid='ref3'>[3]</xref>. In this paper, we have tried to test three cases to investigate the pumping rate and saturation current: 1) two different background materials, iron and Bakelite, were used to compare the magnetic flux linkage reinforcement; 2) two HTS tapes were overlapped to extend the magnetic flux linkage area, and each HTS tape was connected to an HTS coil; and 3) the parallel joint was conducted between the flux-pump and the HTS coil to compose a closed loop for persistent current mode. In order to measure the charging speed and pumping rate, a Hall sensor was installed at the center of the HTS coil.</P>

A Comparative Analysis between ATM based IP routing

Haeryong Lee(이해룡),Kwangroh Park(박광로),Byungchun Jeon(전병천) 한국통신학회 1998 한국통신학회 학술대회논문집 Vol.1998 No.11

Experimental Analysis of Charging Characteristics of HTS Field Coils With HTS Contactless Rotary Excitation Device Considering Various HTS Loads

Lee, Jeyull,Jeon, Haeryong,Han, Seunghak,Kim, Ji Hyung,Hyeon, Chang Ju,Kim, Ho Min,Ko, Tae Kuk,Park, Dong Keun,Yoon, Yong Soo Institute of Electrical and Electronics Engineers 2018 IEEE transactions on applied superconductivity Vol.28 No.3

<P>In this paper, the charging characteristics of high-Tc superconducting (HTS) field coils are analyzed experimentally to verify the efficiency of using HTS contactless rotary excitation devices (CREDs). The HTS CRED is composed of eight HTS rotor strands, which are connected in series with HTS load coils, and eight neodymium permanent magnets (N50). The magnetic field of N50 is approximately 0.14 T when the air gap between the HTS rotor strand and N50 is 8 mm. In order to verify the proper charging method, two types of experiments are performed. In the first experiment, the HTS loads are connected in series and are charged by eight HTS rotor strands of the HTS CRED. In the second, the HTS loads are located along the same axis, and each coil is charged by four HTS rotor strands of the HTS CRED. In these experiments, the currents flowing through the HTS loads are measured for rotor speeds ranging from 50 to 300 r/min.</P>

MPLS망에서의 VPN 서비스 구조 연구

이해룡(Lee Haeryong),박광로(Park Kwangroh),전병천(Jeon Byungchun) 한국통신학회 1998 한국통신학회 학술대회 및 강연회 Vol.1998 No.12

enomenological Analysis for Water Exchange in Bentonite Porewater and Suggestion on the Performance Assessment on the Domestic Disposal Facility for High-level Radioactive Waste

Jaemin Jung,Seong-Su Jeon,Sukhoon Kim,Jeong-Hwan Lee,Haeryong Jung 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.1

Bentonite, a material mainly used in buffer and backfill of the engineering barrier system (EBS) that makes up the deep geological repository, is a porous material, thus porewater could be contained in it. The porewater components will be changed through ‘water exchange’ with groundwater as time passes after emplacement of subsystems containing bentonite in the repository. ‘Water exchange’ is a phenomenon in which porewater and groundwater components are exchanged in the process of groundwater inflow into bentonite, which affects swelling property and radionuclide sorption of bentonite. Therefore, it is necessary to assess conformity with the performance target and safety function for bentonite. Accordingly, we reviewed how to handle the ‘water exchange’ phenomenon in the performance assessment conducted as part of the operating license application for the deep geological repository in Finland, and suggested studies and/or data required for the performance assessment of the domestic disposal facility on the basis of the results. In the previous assessment in Finland, after dividing the disposal site into a number of areas, reference and bounding groundwaters were defined considering various parameters by depth and climate change (i.e. phase). Subsequently, after defining reference and bounding porewaters in consideration of water exchange with porewater for each groundwater type, the swelling and radionuclides sorption of bentonite were assessed through analyzing components of the reference porewater. From the Finnish case, it is confirmed that the following are important from the perspective of water exchange: (a) definition of reference porewater, and (b) variations in cation concentration and cation exchange capacity (CEC) in porewater. For applying items above to the domestic disposal facility, the site-specific parameters should be reflected for the following: structure of the bedrock, groundwater composition, and initial components of bentonite selected. In addition, studies on the following should be required for identifying properties of the domestic disposal site: (1) variations in groundwater composition by subsurface depth, (2) variations in groundwater properties by time frame, and (3) investigation on the bedrock structure, and (4) survey on initial composition of porewater in selected bentonite The results of this study are presumed to be directly applied to the design and performance assessment for buffer and backfill materials, which are important components that make up the domestic disposal facility, given the site-specific data.

A Review on How to Assess the Accessory Mineral Alteration in Bentonite in the Domestic Disposal Facility for High-level Radioactive Waste

Subin Kim,Seong-Su Jeon,Sukhoon Kim,Jeong-Hwan Lee,Haeryong Jung 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.1

For the deep geological repository, engineering barrier system (EBS) is installed to restrict a release of radionuclide, groundwater infiltration, and unintentional human intrusion. Bentonite, mainly used as buffer and backfill materials, is composed of smectite and accessory minerals (e.g. salts, silica). During the post-closure phase, accessory minerals of bentonite may be redistributed through dissolution and precipitation due to thermal-hydraulic gradient formed by decay heat of spent nuclear fuel and groundwater inflow. It should be considered important since this cause canister corrosion and bentonite cementation, which consequently affect a performance of EBS. Accordingly, in this study, we first reviewed the analyses for the phenomenon carried out as part of construction permit and/or operating license applications in Sweden and Finland, and then summarized the prerequisite necessary to apply to the domestic disposal facility in the future. In previous studies in Sweden (SKB) and Finland (POSIVA), the accessory mineral alteration for the post-closure period was evaluated using TOUGHREACT, a kind of thermal-hydro-geochemical code. As a result of both analyses, it was found that anhydrite and calcite were precipitated at the canister surface, but the amount of calcite precipitate was insignificant. In addition, it was observed that precipitate of silica was negligible in POSIVA and there was a change in bentonite porosity due to precipitation of salts in SKB. Under the deep disposal conditions, the alteration of accessory minerals may have a meaningful influence on performance of the canister and buffer. However, for the backfill and closure, this is expected to be insignificant in that the thermal-hydraulic gradient inducing the alteration is low. As a result, for the performance assessment of domestic disposal facility, it is confirmed that a study on the alteration of accessory minerals in buffer bentonite is first required. However, in the study, the following data should reflect the domestic-specific characteristics: (a) detailed geometry of canister and buffer, (b) thermal and physical properties of canister, bentonite and host-rock in the disposal site, (c) geochemical parameters of bentonite, (d) initial composition of minerals and porewater in bentonite, (e) groundwater composition, and (f) decay heat of spent nuclear fuel in canister. It is presumed that insights from case studies for the accessory mineral alteration could be directly applied to the design and performance assessment of EBS, provided that input data specific to the domestic disposal facility is prepared for the assessment required.

A Phenomenological Review on the Dissolution of Montmorillonite by Strong Alkaline Cement Leachates and Suggestion on Requisites for the Assessment in Korea

Beomsu Eom,Seong-su Jeon,Sukhoon Kim,Jeong-Hwan Lee,Haeryong Jung 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.1

In the deep geological repository, a considerable quantity of cementitious materials is generally used for structural stability of subcomponents such as grout and concrete plug of disposition tunnel. Strong alkaline leachates (pH>13) are produced after cement is dissolved by groundwater inflow from bedrock. When the leachates are transported to bentonite porewater (e.g. buffer and backfill) and thereby water exchange occurs, the physical properties of bentonite such as swelling capacity and hydraulic conductivity are changed, which eventually affects the safety function and long-term stability of engineered barrier system (EBS). Thus, in this paper, we reviewed the performance assessment methodology for cement-bentonite interaction in the operating license application for the Finnish deep geological repository, and suggested what to prepare for the analysis on the domestic disposal facility. In Finland, thermal-hydraulic-chemical analysis for dissolution of montmorillonite by alkaline leachates resulting from cement degradation during the saturation of bentonite was carried out using PRECIP code. From this analysis, it was confirmed that effect on pH was considered to be more significant than that on temperature and bentonite saturation. As a result of this analysis, it was predicted that all primary minerals (including montmorillonite, quartz, and calcite) were dissolved and some secondary minerals (e.g. chalcedony and celadonite) was precipitated by alkaline cement leachates transported to the bentonite. In addition, it was shown that silica was preferentially released while the montmorillonite was dissolved, thus cementation of the bentonite was occurred. Through this phenomenon, the swelling capacity of bentonite is reduced and the hydraulic conductivity of bentonite is increased, which have a significant impact on the performance of the buffer and backfill. Considering this, study on spreading of alkaline leachates, which is a condition for dissolution of montmorillonite, is necessary for the performance assessment of the domestic deep geological repository. However, this requires the site-specific data for the following in the disposal site: (a) distribution in fractured bedrock and pore structure (e.g. porosity, pore size distribution and pore morphology) in the bedrock, (b) hydraulic gradient and salinity concentration of groundwater, and (c) flux and velocity of groundwater. Results of this study is considered to be directly utilized to the conceptual design and performance assessment of the deep geological repository in Korea, provided that additional data on microbiological properties of groundwater are obtained for the site selected.